Why did the mutual admiration that the U. S. and Iran once had for each other
break down?

Iran and the United States have had no formal diplomatic relations since April 1980. Pakistan serves as Iran's protecting power in the United States, while Switzerland serves as the United States' protecting power in Iran.

Explanation:

answer; andrew jackson approved nullification by signing it into law,and john calhoun opposed it saying it was unconstitutional;

answer: the risk-return relationship. generally, the higher the potential return of an investment, the higher the risk. there is no guarantee that you will actually get a higher return by accepting more risk. diversification enables you to reduce the risk of your portfolio without sacrificing potential returns.

explanation: